A little different
Hikikomori is actually more like agoraphobia in my opinion. Hikikomori people actually can't bring themselves to go outside of their house. I guess in extreme cases SP can approach that, but usually not from what I've read.
But the Japanese society certainly does contribute to a lot of social disorders, lending evidence to the idea that environment plays a huge factor in development of these conditions, maybe even equally or moreso than biological factors (although my mother also suffers from GAD).
I think my case is unique, though, because I'm a 6'4" white guy with blue eyes in Japan. My SP, since I did not have it when I lived in America but developed it within 3 months of coming to Japan, has been almost completely triggered by the rude habit of Japanese people to stare incessantly at non-Japanese people and segregate them from social interaction. While I understand my condition exacerbates the sensation I'm being stared at and judged, in my case I actually am... which makes it all the harder to deal with. I think the cognitive therapy approach is used to expose sufferers to the reality that their fears of judgement and being stared at are unrealistic, whereas over here, there's nothing unrealistic about it. Any observer could watch a scene with me on a train or walking down the sidewalk here in Japan and blatantly see about half of all the Japanese people anywhere around staring, giving the occasional dirty look, pulling their children 'away to safety', or having rude conversations about me right in front of my face (which comes from the widespread belief by Japanese that their language is incomprehensible by anyone who doesn't look Japanese).
So what does someone in my case do? I don't think trying to trick myself into believing this stuff isn't really happening, and to an overwhelming degree all around me all the time in public, is going to be feasible. Anybody's too smart to deny it if they've spent even a short amount of time in Japan. It's on me to de-emphasize the importance of those idiots' actions. But I've been trying now for 3 years and still suffer increasingly worse symptoms.